Free Steel Truss Design Calculator — AISC 360
Design steel trusses for roof and floor framing — Pratt, Warren, Howe, and custom configurations. The calculator determines member axial forces, checks tension and compression members, verifies slenderness limits, and designs welded or bolted connections at panel points per AISC 360-22, AS 4100 Section 8, EN 1993-1-1, and CSA S16.
Typical trusses: roof trusses spanning 40-120 ft, bridge trusses, long-span floor trusses, open-web steel joists, and space trusses. Members are typically double-angle, HSS, WT, or wide-flange sections.
How to Use
- Select truss configuration: Pratt, Warren, Howe, Fink, or custom.
- Enter span, depth, panel point spacing, and truss spacing.
- Apply loads: roof/dead load, live/snow load, wind uplift, seismic.
- Analyze member forces: top chord, bottom chord, diagonals, verticals.
- Check members: tension yielding/rupture, compression buckling, slenderness.
- Design connections: gusset plates, bolts, welds at panel points.
Design Code Requirements
| Check | AISC 360 | AS 4100 | EN 1993-1-1 | CSA S16 |
|---|---|---|---|---|
| Tension yielding | D2 (phi=0.90) | Cl 7.1 (phi=0.90) | Cl 6.2.3 (gamma_M0=1.0) | Cl 13.2 (phi=0.90) |
| Tension rupture | D3 (phi=0.75) | Cl 7.2 (phi=0.80) | Cl 6.2.3 (gamma_M2=1.25) | Cl 13.2 (phi=0.85) |
| Compression buckling | E3 (phi=0.90) | Cl 6.3 (phi=0.90) | Cl 6.3.1 (chi method) | Cl 13.3 (phi=0.90) |
| Slenderness limits | D1 (L/r ≤ 300) | Cl 7.4 (L/r ≤ 300) | Cl 6.2 | Cl 10.2 (Le/r ≤ 300) |
| Gusset plate design | J4, J5 | Cl 9.2 | Cl 3.10-3.12 | Cl 13.11-13.13 |
Frequently Asked Questions
What is the most efficient truss configuration for long-span roofs? The Warren truss (alternating diagonals with no verticals) is typically the most efficient for spans up to 100 feet because it minimizes member count while maintaining adequate load distribution. For longer spans (100-200+ feet), the Pratt truss (diagonals sloping toward center) is preferred because the longer compression diagonals in the Warren configuration become inefficient.
What slenderness limits apply to truss members? AISC 360-22 Section D1 limits tension member slenderness to L/r ≤ 300 for members subjected to stress reversal (wind or seismic). For compression members, AISC E2 recommends L/r ≤ 200 for main members. The effective length (KL) for in-plane truss buckling is typically 0.5 to 1.0 times the member length depending on end conditions and gusset plate stiffness.
How are truss connections designed at panel points? Truss connections use gusset plates at panel points to connect converging web and chord members. The gusset plate is checked for Whitmore section yielding, block shear, and buckling. Welded connections are common in shop-fabricated trusses; bolted connections are used for field splices. AISC 360 Chapter J and EN 1993-1-8 govern the connection design.
What is the difference between top chord and bottom chord design? The top chord is typically in compression (from roof loads and axial truss action) and is therefore governed by buckling about both axes. The bottom chord is in tension and is governed by net section rupture at bolt holes. Lacing or batten plates may be needed for built-up compression chords. Panel point eccentricity must be considered for both.
Is this truss design calculator free? Yes, completely free with unlimited calculations.
Related pages
- Steel frame analysis
- Tension member design
- Column capacity calculator
- Steel connection checks
- Steel roof truss reference
Disclaimer (educational use only)
This page is provided for general technical information and educational use only. It does not constitute professional engineering advice. All structural designs must be verified by a licensed Professional Engineer (PE) or Structural Engineer (SE). The site operator disclaims liability for any loss or damage arising from the use of this page.